Transient reduction kinetics of NO over Pd-based metallic monoliths

The kinetics and the mechanism of the catalytic reduction of nitrogen oxide s (NOx) by hydrogen were studied over a modified alumina-based palladium mo nolith. Nitrogen, nitrous oxide, ammonia, and water were detected as reacti on products. Transient experiments yielded information about the surface re action mechanisms. The dissociation of NO is the crucial step, dominating t he overall reaction behaviour and that it depends on temperature and on the partial pressure of H-2. A transient kinetic model based on elementary rea ction steps was developed for a stoichiometric mixture of (NO + H-2)/Ar. Th e model was based on the transient plug flow concept. The parameters of mod el were determined by regression analysis. The comparison of model simulati ons with the experimental data revealed that the model was able to describe the transient NO reduction kinetics. (C) 2001 Published by Elsevier Scienc e Ltd.